Gwyneth Paltrow and Shailene Woodley have both recently shared their love for the all-natural teeth-whitening trick known as "oil pulling." "I just started 'oil pulling,' which is when you swish coconut oil around [in your mouth] for 20 minutes, and it's supposed to be great for oral health and making your teeth white," the newly single Goop founder told E! News.

Woodley also takes part in the ancient Ayurvedic technique for better oral health like stronger gums. "It’s amazing!" the Divergent star told Into the Gloss. "It really makes your teeth whiter, because the plaque on your teeth is not water soluble, it’s fat-soluble. So the lipids have to dissolve in fats, which is why oil works in your mouth. I prefer sesame oil, but they’re both good."

Even though Paltrow and Woodley swear by the practice (and we would never, ever willingly go against Goop or Beatrice), does it have an actual medical foundation? Turns out, it's not as cray-cray as you think. "It's probably the most harmless natural remedy. There's no downside," Dr. Marc Lowenberg, a New York City-based cosmetic dentist, tells Us Weekly.

"The toxins in your body are fat-soluble so they join with the oil and are removed when you spit it out," he says. "Since the mouth is loaded with plaque, it makes sense that there would be a reduction."

Lowenberg recommends oil pulling for 15 to 20 minutes first thing in the morning before you eat or drink anything. If swishing oil for that long seems like a lot to swallow then distract yourself with household chores. "You can move around, take a shower," he says.

After you spit (into the garbage, not sink since it'll clog the drains), use a tongue scraper from the back to the front to remove the coat of oil left on your tongue.

Are you going to try oil-pulling? Tweet with @UsWeekly using #stylebyUs!